Ann Thorac Surg 2005;79:691-693
© 2005 The Society of Thoracic Surgeons
Case report
Facilitated MIDCAB Using a Magnetic Coupling Device
Volkmar Falk, MD, PhDa,*,
Thomas Walther, MD, PhDa,
Stephan Jacobs, MDa,
Randall K. Wolf, MDb,
Friedrich W. Mohr, MD, PhDa
a Department of Cardiac Surgery, Heartcenter, University of Leipzig, Columbus, Ohio, Germany
b Department of Surgery, Ohio State University Medical Center, Columbus, Ohio, Germany
Accepted for publication April 1, 2003.
* Address reprint requests to Dr Falk, Klinik für Herzchirurgie, Universität Leipzig, Herzzentrum, Strümpellstr 39, 04289 Leipzig, Germany.
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Abstract
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A 59-year-old male with chronic occlusion of the left anterior descending coronary artery underwent a minimally invasive direct coronary artery bypass procedure using the second generation of a magnetic anastomotic coupling device. Postoperative angiogram demonstrated excellent patency and flow.
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Introduction
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Minimally invasive direct coronary artery bypass (MIDCAB) has evolved into a reliable technique for revascularization of the left anterior descending coronary artery (LAD) with patency results similar to conventional coronary artery bypass grafting [1, 2]. The limited access makes the anastomosis technically more challenging. New methods to facilitate minimally invasive anastomoses are therefore being developed [3].
We report the case of a 59-year-old male with proximal occlusion of the left anterior descending artery who underwent MIDCAB grafting using the second generation of a new magnetic vascular positioner (MVP, Ventrica, Freemont, CA). Recently reported clinical results with the first-generation device have demonstrated excellent patency in arterial grafts to the LAD [4]. To avoid lateral leakage that occasionally occurred with placement of the first-generation device and to decrease the amount of foreign material exposed to the bloodstream, some modifications were made. In the new device, the internal magnets are held in place by two external magnets placed outside the vessel on the lateral walls [Figure 1 ]. This also increases the effective orifice area (6.0 mm) [2] compared with the first-generation device. The new delivery system separates the actuating trigger from the actual delivery platform, decreasing the likelihood of unintended motion of the delivery platform during actuation. The new device is being evaluated in an ongoing multisite trial. In this institution it is being exclusively used in beating heart surgery.
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Fig 1. Second-generation magnetic vascular positioner. The internal magnets are each held in place by two lateral magnets that have no contact with the bloodstream.
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After informed consent was obtained, 150 mg clopidogrel and 100 mg aspirin were given the day before surgery. Surgery was performed under general anesthesia. After single-lung ventilation was established, a small anterolateral thoracotomy in the 4th intercostal space was performed. The left internal thoracic artery (ITA) was harvested under direct vision and, after heparinization (activated clotting time of 300 seconds), transected distally. The pericardium was opened and the midportion of the LAD was identified. A snare was placed proximal to the anastomotic site for inflow occlusion. The distal ITA was skeletonized and a sharp 4.5-mm arteriotomy was made guided by a sizer held close to the artery. The MVP delivery system device was positioned inside the ITA graft and, after proper seating, the lateral magnets were released. Next, the LAD was temporarily occluded and a 4.5-mm arteriotomy was made in the LAD. The second magnet was then placed in the LAD and the lateral magnets were released. After confirming the absence of excess tissue overlapping the internal magnets, graft and coronary vessels were attached by the magnetic attraction of the two magnets. A clip was placed on the free distal end of the ITA next to the magnet, creating a functional end-to-side anastomosis. After 10 minutes the LAD was reperfused by releasing the proximal snare. There was no leakage from the anastomosis. Transit time Doppler flow measurement yielded a flow of 42 mL/min. The left lung was inflated and the wound was closed in a standard fashion. Postoperative angiography revealed excellent graft patency and TIMI III flow [Figs 2 and 3]. The patient was discharged after an uneventful course on the 6th postoperative day.
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Fig 2. Native coronary angiogram of the left coronary artery (left anterior oblique view) shows the magnetic vascular positioner (MVP) placed in the chronically occluded left anterior descending coronary artery (LAD).
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Fig 3. Angiographic view (left anterior oblique 90°) demonstrating patency of the internal thoracic artery and excellent flow through the anastomosis.
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Comment
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This is the first report of the clinical use of an anastomotic device other than clips in a limited-access coronary operation. It demonstrates the feasibility of this technology in a confined space that imposes a number of anatomic and technical constraints on the surgeon [5] and that have partly prevented the widespread use of the MIDCAB operation. The magnetic port creates a uniform anastomosis with a defined orifice area and eliminates the variability of conventional suturing. Although this ensures a standardized anastomosis, this device may not always be applicable because the current-generation device requires a relatively disease-free target site. In calcified arteries the MVP anastomosis cannot be tailored to the anatomic conditions. In its current design, the MVP is restricted to cases with a large recipient vessel and only little distal disease, such as the one presented here. Further evolution of the delivery system in a minimally invasive environment is clearly warranted and is being pursued. The current-generation device, which was designed for open coronary artery bypass graft techniques, does not meet all the requirements for a limited access or endoscopic environment. Necessary changes might include minimizing the delivery platform to enhance the visualization of the anastomotic site during placement and deployment, and during attraction of the magnets. Misalignment can be corrected, but requires removal of multiple pieces of the magnet. A more integrated design may prevent misalignment. The development of a nonmagnetic spreader and stabilizer for MIDCAB would prevent attraction of the graft to metal parts other than the anastomotic port in the target vessel. The use of aspirin and clopidogrel clearly increases the risk for postoperative bleeding as was demonstrated in the first clinical trial [4]. Future developments may therefore include drug-eluting surfaces, potentially eliminating the need for a rigid anticoagulant regimen.
In summary, the MVP system may allow for the creation of a standardized anastomosis in MIDCAB pending some changes of the current configuration.
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References
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- Diegeler A, Thiele H, Falk V, et al. Comparison of stenting with minimally invasive bypass surgery for stenosis of the left anterior descending coronary artery. N Engl J Med. 2002;347:561–566[Abstract/Free Full Text]
- Mack MJ, Osborne JA, Shennib H. Arterial graft patency in coronary artery bypass grafting: what do we really know? Ann Thorac Surg. 1998;66:1055–1059[Abstract/Free Full Text]
- Subramanian VA, Fonger JD, Connolly MW. Facilitated vascular anastomosis in coronary bypass surgery. Sem Thorac Cardiovasc Surg. 2002;14:89–100[Medline]
- Klima U, Falk V, Moritz A, Mohr FW, Haverich A, Wimmer-Greinecker G. Magnetic vascular coupling in coronary artery bypass grafting: a multicenter trial. J Thorac Cardiovasc Surg, in press
- Falk V. Manual control and tracking—a human factor analysis relevant for beating heart surgery. Ann Thorac Surg. 2002;74:624–628[Abstract/Free Full Text]
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Abstract
Introduction
